Amid the outbreak of the Nipah virus, the Kerala government today asked travellers to avoid visiting four northern districts of the state - Kozhikode, Malappuram, Wayanad and Kannur. In an advisory issued by Health Secretary Rajeev Sadanandan, it was stated that travelling to any part of Kerala was safe. But if travellers wished to be extra cautious, they may avoid the four districts, it said. "A few cases of infection by Nipah virus have been reported from Kozhikode district in Kerala. The infection remains highly localised, all cases being linked to one family," the advisory said. Surveillance by the government is being conducted in Kozhikode district, from where most of the cases were reported, and in the neighbouring districts of Malappuram, Wayanad and Kannur, it said. "The Health department is taking effective steps for management of reported cases and surveillance through tracing of the contact of these persons. The situation remains under control," the advisory said. Meanwhile, 2,000 Ribavirin tablets, an antiviral medicine, have already reached Kozhikode. Another batch of 8,000 tablets are expected to be delivered later in the day, Health department sources said. Ten persons have died of Nipah virus so far in Kozhikode and Malappuram districts. Two more persons who died of high fever are suspected to have contracted the virus. Nipah virus (NiV) infection is a newly emerging zoonosis that causes severe disease in both animals and humans. The natural host of the virus are fruit bats of the Pteropodidae family, Pteropus genus.